“Extremely Loud & Incredibly Close” is a handsomely polished, thoughtfully wrapped Hollywood production about the national tragedy of Sept. 11, 2001, that seems to have forever redefined words such as “unthinkable,” “unforgivable” and “catastrophic.”

It also has redefined our expectations of filmmakers who try to examine the still-aching wound — and perhaps explains why most films about Sept. 11 haven’t resonated with audiences. Mindful of that, director Stephen Daldry has taken great care in looking at it through the eyes of a precocious New York City boy in a film filled with both sentiment and substance.

Finding the right balance was critical to making any adaptation of Jonathan Safran Foer’s provocative novel work. However, Daldry is a filmmaker who’s equally sensitive and bold in handling films with heavy emotional and political content as he has in “Billy Elliot,” “The Hours” and “The Reader,” all of which earned him Oscar nominations.

Like the novel that inspired the film, screenwriter Eric Roth (“Munich”) has brought things back to ground zero through the story of one family torn asunder by the World Trade Center attacks. So it seems a smart choice to put two quintessentially heartland stars in Tom Hanks and Sandra Bullock at its center. It makes acceptance easier, offense harder.

They portray Thomas and Linda Schell, the lost father and grieving mother of Oskar, an 11-year-old played by talented first-timer Thomas Horn as a frenetic bit of energy struggling to make sense of what he calls “the worst day.” The film begins framing that day with scraps of images — paper fluttering like confetti from a skyscraper, smoke billowing out of its windows, a man falling, though against a blue sky and white clouds and with everything in slow motion, it looks not so terrifying as what we saw in news clips of that day.

Woven through all the moments, Oskar’s very specific journey unfolds, the memories of his past guiding an uncertain future, with Horn narrating much of what’s running through his mind. He is a naturally anxious boy, mildly autistic — fearful in ways his father had tried to help mitigate with intricate explorations of the city, a search for the mysteriously missing sixth borough of New York City chief among them.

Though there are many themes coursing through this movie, its primary concern is how anyone copes with a loss like this. In Oskar’s case, it’s the loss not only of a father, but his best friend. In Hanks’ hands, Thomas is kind, funny, clever. He also becomes the film’s primary source of comfort.

Oskar’s world starts off as a very narrow one. There is his working mom, with Bullock effectively dimming her normal bright light to play Oskar’s not always likable mom, and John Goodman’s insult-trading doorman offering some comic relief. The boy’s main confidant, at least initially, is his grandmother. Played by veteran stage actress Zoe Caldwell (“The Prime of Miss Jean Brodie”), she lives in the facing apartment building, ideal for walkie-talkie conversations late at night when Oskar’s worries escalate. Her apartment also houses the mysterious Renter (Max von Sydow), who will figure into Oskar’s life in significant ways.

While home is a claustrophobic apartment, captured with tight shots of tight corners, the film opens up and the camera pulls back as Oskar’s world begins expanding after he discovers a key hidden in his father’s closet. Convinced that it will reveal something important if only he can find the lock, he sets out to cover the five boroughs in search of the person whose name is on the envelope that held the key.

That search becomes the engine that drives the rest of the film. This also becomes the movie’s treatise on healing as it takes Oskar into the homes of the traumatized nation of ordinary people, some coping, others not; his encounter with Viola Davis’ Abby Black is especially moving.

Given its polarizing subject and this much raw emotion, the film probably is destined to be divisive. Some will be bothered by the sentiment, others won’t think it goes far enough or deep enough, still others will resent the movie for even trying to examine the wound. There are certainly big, capital-letter themes explored here: Death. Sorrow. Forgiveness. Reconciliation. Through the boy, Daldry brings it all down to a human level. “Extremely Loud” won’t be the last cinematic word on Sept. 11, but it proves to be an eloquent one.